Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 508 insertions, 0 deletions

diff --git a/tools/docs/kdoc_diff b/tools/docs/kdoc_diff
new file mode 100755
index 000000000..1aa16bdcc
--- /dev/null
+++ b/tools/docs/kdoc_diff
@@ -0,0 +1,508 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+# Copyright(c) 2026: Mauro Carvalho Chehab <mchehab@kernel.org>.
+#
+# pylint: disable=R0903,R0912,R0913,R0914,R0915,R0917
+
+"""
+docdiff - Check differences between kernel‑doc output between two different
+commits.
+
+Examples
+--------
+
+Compare the kernel‑doc output between the last two 5.15 releases::
+
+    $ kdoc_diff v6.18..v6.19
+
+Both outputs are cached
+
+Force a complete documentation scan and clean any previous cache from
+6.19 to the current HEAD::
+
+    $ kdoc_diff 6.19.. --full --clean
+
+Check differences only on a single driver since origin/main::
+
+    $ kdoc_diff origin/main drivers/media
+
+Generate an YAML file and use it to check for regressions::
+
+    $ kdoc_diff HEAD~ drivers/media --regression
+
+
+"""
+
+import os
+import sys
+import argparse
+import subprocess
+import shutil
+import re
+import signal
+
+from glob import iglob
+
+
+SRC_DIR = os.path.dirname(os.path.realpath(__file__))
+WORK_DIR = os.path.abspath(os.path.join(SRC_DIR, "../.."))
+
+KDOC_BINARY = os.path.join(SRC_DIR, "kernel-doc")
+KDOC_PARSER_TEST = os.path.join(WORK_DIR, "tools/unittests/test_kdoc_parser.py")
+
+CACHE_DIR = ".doc_diff_cache"
+YAML_NAME = "out.yaml"
+
+DIR_NAME = {
+    "full": os.path.join(CACHE_DIR, "full"),
+    "partial": os.path.join(CACHE_DIR, "partial"),
+    "no-cache": os.path.join(CACHE_DIR, "no_cache"),
+    "tmp": os.path.join(CACHE_DIR, "__tmp__"),
+}
+
+class GitHelper:
+    """Handles all Git operations"""
+
+    def __init__(self, work_dir=None):
+        self.work_dir = work_dir
+
+    def is_inside_repository(self):
+        """Check if we're inside a Git repository"""
+        try:
+            output = subprocess.check_output(["git", "rev-parse",
+                                              "--is-inside-work-tree"],
+                                             cwd=self.work_dir,
+                                             stderr=subprocess.STDOUT,
+                                             universal_newlines=True)
+
+            return output.strip() == "true"
+        except subprocess.CalledProcessError:
+            return False
+
+    def is_valid_commit(self, commit_hash):
+        """
+        Validate that a ref (branch, tag, commit hash, etc.) can be
+        resolved to a commit.
+        """
+        try:
+            subprocess.check_output(["git", "rev-parse", commit_hash],
+                                    cwd=self.work_dir,
+                                    stderr=subprocess.STDOUT)
+            return True
+        except subprocess.CalledProcessError:
+            return False
+
+    def get_short_hash(self, commit_hash):
+        """Get short commit hash"""
+        try:
+            return subprocess.check_output(["git", "rev-parse", "--short",
+                                            commit_hash],
+                                           cwd=self.work_dir,
+                                           stderr=subprocess.STDOUT,
+                                           universal_newlines=True).strip()
+        except subprocess.CalledProcessError:
+            return ""
+
+    def has_uncommitted_changes(self):
+        """Check for uncommitted changes"""
+        try:
+            subprocess.check_output(["git", "diff-index",
+                                     "--quiet", "HEAD", "--"],
+                                    cwd=self.work_dir,
+                                    stderr=subprocess.STDOUT)
+            return False
+        except subprocess.CalledProcessError:
+            return True
+
+    def get_current_branch(self):
+        """Get current branch name"""
+        return subprocess.check_output(["git", "branch", "--show-current"],
+                                        cwd=self.work_dir,
+                                        universal_newlines=True).strip()
+
+    def checkout_commit(self, commit_hash, quiet=True):
+        """Checkout a commit safely"""
+        args = ["git", "checkout", "-f"]
+        if quiet:
+            args.append("-q")
+        args.append(commit_hash)
+        try:
+            subprocess.check_output(args, cwd=self.work_dir,
+                                    stderr=subprocess.STDOUT)
+
+            # Double-check if branch actually switched
+            branch = self.get_short_hash("HEAD")
+            if commit_hash != branch:
+                raise RuntimeError(f"Branch changed to '{branch}' instead of '{commit_hash}'")
+
+            return True
+        except subprocess.CalledProcessError as e:
+            print(f"ERROR: Failed to checkout {commit_hash}: {e}",
+                  file=sys.stderr)
+            return False
+
+
+class CacheManager:
+    """Manages persistent cache directories"""
+
+    def __init__(self, work_dir):
+        self.work_dir = work_dir
+
+    def initialize(self):
+        """Create cache directories if they don't exist"""
+        for dir_path in DIR_NAME.values():
+            abs_path = os.path.join(self.work_dir, dir_path)
+            if not os.path.exists(abs_path):
+                os.makedirs(abs_path, exist_ok=True, mode=0o755)
+
+    def get_commit_cache(self, commit_hash, path):
+        """Generate cache path for a commit"""
+        hash_short = GitHelper(self.work_dir).get_short_hash(commit_hash)
+        if not hash_short:
+            hash_short = commit_hash
+
+        return os.path.join(path, hash_short)
+
+class KernelDocRunner:
+    """Runs kernel-doc documentation generator"""
+
+    def __init__(self, work_dir, kdoc_binary):
+        self.work_dir = work_dir
+        self.kdoc_binary = kdoc_binary
+        self.kdoc_files = None
+
+    def find_kdoc_references(self):
+        """Find all files marked with kernel-doc:: directives"""
+        if self.kdoc_files:
+            print("Using cached Kdoc refs")
+            return self.kdoc_files
+
+        print("Finding kernel-doc entries in Documentation...")
+
+        files = os.path.join(self.work_dir, 'Documentation/**/*.rst')
+        pattern = re.compile(r"^\.\.\s+kernel-doc::\s*(\S+)")
+        kdoc_files = set()
+
+        for file_path in iglob(files, recursive=True):
+            try:
+                with open(file_path, 'r', encoding='utf-8') as fp:
+                    for line in fp:
+                        match = pattern.match(line.strip())
+                        if match:
+                            kdoc_files.add(match.group(1))
+
+            except OSError:
+                continue
+
+        self.kdoc_files = list(kdoc_files)
+
+        return self.kdoc_files
+
+    def gen_yaml(self, yaml_file, kdoc_files):
+        """Runs kernel-doc to generate a yaml file with man and rst."""
+        cmd = [self.kdoc_binary, "--man", "--rst", "--yaml", yaml_file]
+        cmd += kdoc_files
+
+        print(f"YAML regression test file will be stored at: {yaml_file}")
+
+        try:
+            subprocess.check_call(cmd, cwd=self.work_dir,
+                                  stdout=subprocess.DEVNULL,
+                                  stderr=subprocess.DEVNULL)
+        except subprocess.CalledProcessError:
+            return False
+
+        return True
+
+    def run_unittest(self, yaml_file):
+        """Run unit tests with the generated yaml file"""
+        cmd = [KDOC_PARSER_TEST, "-q", "--yaml", yaml_file]
+        result = subprocess.run(cmd, cwd=self.work_dir)
+
+        if result.returncode:
+            print("To check for problems, try to run it again with -v\n")
+            print("Use -k <regex> to filter results\n\n\t$", end="")
+            print(" ".join(cmd) + "\n")
+
+        return True
+
+    def normal_run(self, tmp_dir, output_dir, kdoc_files):
+        """Generate man, rst and errors, storing them at tmp_dir."""
+        os.makedirs(tmp_dir, exist_ok=True)
+
+        try:
+            with open(os.path.join(tmp_dir, "man.log"), "w", encoding="utf-8") as out:
+                subprocess.check_call([self.kdoc_binary, "--man"] + kdoc_files,
+                                      cwd=self.work_dir,
+                                      stdout=out, stderr=subprocess.DEVNULL)
+
+            with open(os.path.join(tmp_dir, "rst.log"), "w", encoding="utf-8") as out:
+                with open(os.path.join(tmp_dir, "err.log"), "w", encoding="utf-8") as err:
+                    subprocess.check_call([self.kdoc_binary, "--rst"] + kdoc_files,
+                                          cwd=self.work_dir,
+                                          stdout=out, stderr=err)
+        except subprocess.CalledProcessError:
+            return False
+
+        if output_dir:
+            os.replace(tmp_dir, output_dir)
+
+        return True
+
+    def run(self, commit_hash, tmp_dir, output_dir, kdoc_files, is_regression,
+            is_end):
+        """Run kernel-doc on its several ways"""
+        if not kdoc_files:
+            raise RuntimeError("No kernel-doc references found")
+
+        git_helper = GitHelper(self.work_dir)
+        if not git_helper.checkout_commit(commit_hash, quiet=True):
+            raise RuntimeError(f"ERROR: can't checkout commit {commit_hash}")
+
+        print(f"Processing {commit_hash}...")
+
+        if not is_regression:
+            return self.normal_run(tmp_dir, output_dir, kdoc_files)
+
+        yaml_file = os.path.join(tmp_dir, YAML_NAME)
+
+        if not is_end:
+            return self.gen_yaml(yaml_file, kdoc_files)
+
+        return self.run_unittest(yaml_file)
+
+class DiffManager:
+    """Compare documentation output directories with an external diff."""
+    def __init__(self, diff_tool="diff", diff_args=None):
+        self.diff_tool = diff_tool
+        # default: unified, no context, ignore whitespace changes
+        self.diff_args = diff_args or ["-u0", "-w"]
+
+    def diff_directories(self, dir1, dir2):
+        """Compare two directories using an external diff."""
+        print(f"\nDiffing {dir1} and {dir2}:")
+
+        dir1_files = set()
+        dir2_files = set()
+        has_diff = False
+
+        for root, _, files in os.walk(dir1):
+            for file in files:
+                dir1_files.add(os.path.relpath(os.path.join(root, file), dir1))
+        for root, _, files in os.walk(dir2):
+            for file in files:
+                dir2_files.add(os.path.relpath(os.path.join(root, file), dir2))
+
+        common_files = sorted(dir1_files & dir2_files)
+        for file in common_files:
+            f1 = os.path.join(dir1, file)
+            f2 = os.path.join(dir2, file)
+
+            cmd = [self.diff_tool] + self.diff_args + [f1, f2]
+            try:
+                result = subprocess.run(
+                    cmd, capture_output=True, text=True, check=False
+                )
+                if result.stdout:
+                    has_diff = True
+                    print(f"\n{file}")
+                    print(result.stdout, end="")
+            except FileNotFoundError:
+                print(f"ERROR: {self.diff_tool} not found")
+                sys.exit(1)
+
+        # Show files that exist only in one directory
+        only_in_dir1 = dir1_files - dir2_files
+        only_in_dir2 = dir2_files - dir1_files
+        if only_in_dir1 or only_in_dir2:
+            has_diff = True
+            print("\nDifferential files:")
+            for f in sorted(only_in_dir1):
+                print(f"  - {f} (only in {dir1})")
+            for f in sorted(only_in_dir2):
+                print(f"  + {f} (only in {dir2})")
+
+        if not has_diff:
+            print("\nNo differences between those two commits")
+
+
+class SignalHandler():
+    """Signal handler class."""
+
+    def restore(self, force_exit=False):
+        """Restore original HEAD state."""
+        if self.restored:
+            return
+
+        print(f"Restoring original branch: {self.original_head}")
+        try:
+            subprocess.check_call(
+                ["git", "checkout", "-f", self.original_head],
+                cwd=self.git_helper.work_dir,
+                stderr=subprocess.STDOUT,
+            )
+        except subprocess.CalledProcessError as e:
+            print(f"Failed to restore: {e}", file=sys.stderr)
+
+        for sig, handler in self.old_handler.items():
+            signal.signal(sig, handler)
+
+        self.restored = True
+
+        if force_exit:
+            sys.exit(1)
+
+    def signal_handler(self, sig, _):
+        """Handle interrupt signals."""
+        print(f"\nSignal {sig} received. Restoring original state...")
+
+        self.restore(force_exit=True)
+
+    def __enter__(self):
+        """Allow using it via with command."""
+        for sig in [signal.SIGINT, signal.SIGTERM]:
+            self.old_handler[sig] = signal.getsignal(sig)
+            signal.signal(sig, self.signal_handler)
+
+        return self
+
+    def __exit__(self, *args):
+        """Restore signals at the end of with block."""
+        self.restore()
+
+    def __init__(self, git_helper, original_head):
+        self.git_helper = git_helper
+        self.original_head = original_head
+        self.old_handler = {}
+        self.restored = False
+
+def parse_commit_range(value):
+    """Handle a commit range."""
+    if ".." not in value:
+        begin = value
+        end = "HEAD"
+    else:
+        begin, _, end = value.partition("..")
+        if not end:
+            end = "HEAD"
+
+    if not begin:
+        raise argparse.ArgumentTypeError("Need a commit begginning")
+
+
+    print(f"Range: {begin} to {end}")
+
+    return begin, end
+
+
+def main():
+    """Main code"""
+    parser = argparse.ArgumentParser(description="Compare kernel documentation between commits")
+    parser.add_argument("commits", type=parse_commit_range,
+                        help="commit range like old..new")
+    parser.add_argument("files", nargs="*",
+                        help="files to process – if supplied the --full flag is ignored")
+
+    parser.add_argument("--full", "-f", action="store_true",
+                        help="Force a full scan of Documentation/*")
+
+    parser.add_argument("--regression", "-r", action="store_true",
+                        help="Use YAML format to check for regressions")
+
+    parser.add_argument("--work-dir", "-w", default=WORK_DIR,
+                        help="work dir (default: %(default)s)")
+
+    parser.add_argument("--clean", "-c", action="store_true",
+                        help="Clean caches")
+
+    args = parser.parse_args()
+
+    if args.files and args.full:
+        raise argparse.ArgumentError(args.full,
+                                     "cannot combine '--full' with an explicit file list")
+
+    work_dir = os.path.abspath(args.work_dir)
+
+    # Initialize cache
+    cache = CacheManager(work_dir)
+    cache.initialize()
+
+    # Validate git repository
+    git_helper = GitHelper(work_dir)
+    if not git_helper.is_inside_repository():
+        raise RuntimeError("Must run inside Git repository")
+
+    old_commit, new_commit = args.commits
+
+    old_commit = git_helper.get_short_hash(old_commit)
+    new_commit = git_helper.get_short_hash(new_commit)
+
+    # Validate commits
+    for commit in [old_commit, new_commit]:
+        if not git_helper.is_valid_commit(commit):
+            raise RuntimeError(f"Commit '{commit}' does not exist")
+
+    # Check for uncommitted changes
+    if git_helper.has_uncommitted_changes():
+        raise RuntimeError("Uncommitted changes present. Commit or stash first.")
+
+    runner = KernelDocRunner(git_helper.work_dir, KDOC_BINARY)
+
+    # Get files to be parsed
+    cache_msg = " (results will be cached)"
+    if args.full:
+        kdoc_files = ["."]
+        diff_type = "full"
+        print(f"Parsing all files at {work_dir}")
+    if not args.files:
+        diff_type = "partial"
+        kdoc_files = runner.find_kdoc_references()
+        print(f"Parsing files with kernel-doc markups at {work_dir}/Documentation")
+    else:
+        diff_type = "no-cache"
+        cache_msg = ""
+        kdoc_files = args.files
+
+    tmp_dir = DIR_NAME["tmp"]
+    out_path = DIR_NAME[diff_type]
+
+    if not args.regression:
+        print(f"Output will be stored at: {out_path}{cache_msg}")
+
+    # Just in case - should never happen in practice
+    if not kdoc_files:
+        raise argparse.ArgumentError(args.files,
+                                        "No kernel-doc references found")
+
+    original_head = git_helper.get_current_branch()
+
+    old_cache = cache.get_commit_cache(old_commit, out_path)
+    new_cache = cache.get_commit_cache(new_commit, out_path)
+
+    with SignalHandler(git_helper, original_head):
+        if args.clean or diff_type == "no-cache":
+            for cache_dir in [old_cache, new_cache]:
+                if cache_dir and os.path.exists(cache_dir):
+                    shutil.rmtree(cache_dir)
+
+        if args.regression or not os.path.exists(old_cache):
+            old_success = runner.run(old_commit, tmp_dir, old_cache, kdoc_files,
+                                    args.regression, False)
+        else:
+            old_success = True
+
+        if args.regression or not os.path.exists(new_cache):
+            new_success = runner.run(new_commit, tmp_dir, new_cache, kdoc_files,
+                                    args.regression, True)
+        else:
+            new_success = True
+
+    if not (old_success and new_success):
+        raise RuntimeError("Failed to generate documentation")
+
+    if not args.regression:
+        diff_manager = DiffManager()
+        diff_manager.diff_directories(old_cache, new_cache)
+
+if __name__ == "__main__":
+    main()